Our increasingly mobile and mechanized society uses a variety of different fuels (e.g., gasoline, diesel fuel, ethanol, etc.) as energy. Liquid fuels are generally stored in liquid reservoirs such as underground storage tanks, above ground tanks, or any of a variety of different containers. Typically, liquid fuel reservoirs have inlets and outlets through which fuel can be added to and/or removed from the reservoir. These inlets and outlets may typically consist of a riser pipe extending from the reservoir. Internal to the riser pipe is a drop tube that typically includes an overfill valve adapted to respond once a predetermined level is reached in the liquid reservoir. To simplify manufacture and assembly, it is also known to provided the drop tube in a plurality of segments that are fastened together in series to form an overall drop tube assembly. As shown in U.S. Pat. No. 4,986,320, for example, the drop tube assembly includes an intermediate drop tube segment having opposed ends that are each correspondingly fastened to an upper and lower drop tube segment with fasteners extending through the respective walls of the segments.
Such configurations have proven to be very effective. To further enhance the beneficial nature of previous drop tube assemblies, there is a desire to provide a substantially fluid tight seal at the fastening location between the drop tube segments. A fluid tight seal may reduce or prevent fluid, such as vapor, from being released from the ullage area of the reservoir to the interior of the drop tube that might act as a chimney to vent the fluid to the surrounding atmosphere and potentially create an environmental concern.
To address potential concerns of vapor leakage, it is known to provide fastening sections with an epoxy layer to provide a fluid-tight seal at potential leak points. For example, it is known to provide a drop tube assembly, as shown in U.S. Pat. No. 4,986,320, with a conventional drop tube segment 500 described with respect to FIGS. 1–4 and 4A of the drawings herein. As shown in FIG. 4, the conventional drop tube segment 500 may include a fastening section 509 adapted to facilitate attachment between the drop tube segment 500 and another conventional drop tube segment that can be arranged as an upper drop tube segment 620. The conventional drop tube segment 500 can be attached to the conventional upper drop tube segment 620 to form a conventional drop tube assembly 660. As described more fully below, the conventional fastening arrangement includes an epoxy layer, such as a layer of Loctite® epoxy-sealant for use as a cold weld bonding compound.
As shown in FIG. 1, the conventional drop tube segment 500 includes a conduit 502 with a first end portion 504 (see FIG. 3) and a second end portion 506. The first end portion 504 includes a wall 511 with an inner surface 511a and an outer surface 511b. Three fastener receiving structures 507a, 507b, 507c are radially disposed on the wall 511. In addition, each fastener receiving structure 507a, 507b, 507c comprises an opening that extends between the inner surface 511a and the outer surface 511b of the wall 511, along respective corresponding axes 508a, 508b, 508c, such that the openings comprise through openings that might permit fluid communication between the inner surface 511a and the outer surface 511b. 
The drop tube segment 500 further includes a valve assembly 510 with a valve member 512 and a bracket 514. The bracket 514 is adapted to pivotally associate the valve member 512 with the first end portion 504 of the conduit 502. As shown, the bracket 514 includes a lower portion 516, a first pivot support member 518 and a second pivot support member 520. The first and second pivot support member 518, 520 are tack welded to the lower portion 516. The bracket may then be mounted to a mounting surface of the first end portion 504 of the conduit 520 with a pair of mounting screws 524.
The valve assembly 510 further includes a float 530 and a linkage device 570 pivotally connected with the valve member 512 and in communication with the float 530 wherein the float 530 may facilitate in adjusting position of the valve member 512 with respect to the first end portion 504 in response to a liquid level in a liquid reservoir.
As shown in FIGS. 1 and 3, the drop tube segment 500 is also known to include a conventional adjustable stop member 588 located below an O-ring sealing member 505 and adapted to engage the linkage device 570 to limit a movement of the linkage device 570. As shown in FIG. 1, the adjustable stop member 588 is located downstream of the O-ring sealing member 505 due to the limited space available upstream the O-ring sealing member 505. For example, in the orientation shown in FIG. 1, any attempt to locate the adjustable stop member above the O-ring sealing member 505 would necessarily interfere with the lower portion 516 of the bracket 514.
During assembly, the previously-mentioned upper drop tube segment 620 is provided that includes an upper conduit 622 with a first end portion 624 and a second end portion 626. As shown in FIG. 4, the second end portion 626 of the upper conduit 622 is inserted over the first end portion 504 of the conduit 502 such that apertures in the upper conduit 622 are each aligned with a corresponding fastener receiving structure 507a, 507b, 507c. A fastener 646 may then be inserted through each aperture to engage a crimped portion and a corresponding one of the fastener receiving structures 507a, 507b, 507c. An epoxy layer 648 may be effective to fill in any grooves and/or other imperfections in the outer circumferential surface of the O-ring sealing member 505 to provide a fluid tight seal between the drop tube segment 500 and the upper drop tube segment 620. Similarly, another epoxy layer 650 may be applied about the head of each fastener 646 in order to provide a fluid tight seal at each of the fastener receiving structures 507a, 507b, 507c. 
As mentioned previously, the adjustable stop member 588 is located downstream of the O-ring sealing member 505. For example, in the orientation shown in FIG. 1, the adjustable stop member 588 is located below the O-ring sealing member 505. As shown in FIG. 4A, a potential leak path exists at the interface 588a between the adjustable stop member 588 and the wall 511 since the adjustable stop member 588 is located downstream of the O-ring sealing member 505. Such a leak path might permit fluid, such as vapor, from being released from the ullage area of the reservoir to the interior of the drop tube and thereafter released to the surrounding atmosphere and potentially create an environmental concern. The previously-mentioned epoxy layer 648 may be effective to inhibit, such as prevent, such fluid leakage at the interface 588a. Still further, another epoxy layer 652 may be applied about a periphery of the drop tube assembly 660 at a circumferential joint 629 between the upper conduit 622 and the conduit 502 to further inhibit, such as prevent fluid leakage at the interface 588a. 
Application of an epoxy layer to provide fluid-tight sealing has proven very beneficial to reduce fluid vapor leakage. However, the addition of an epoxy layer typically greatly lengthens the installation process and the epoxy layer must cure for an extended period of time before the drop tube assembly may be installed with respect to the liquid reservoir. Currently, there is a need for drop tube assemblies that comprise a plurality of sections that may be connected together for immediate installation with respect to the liquid reservoir while providing a fluid seal at the fastening location between the drop tube segments.